This invention relates to box or case sealers for closing the open ends of cardboard boxes or cartons.
In the packaging industry, many products are packed in cardboard boxes or cartons for shipping. Often, one end of the box, namely the bottom, is sealed shut before the box is filled, and after the box is filled, the open top end of the box usually has end and side flaps that are folded inwardly and downwardly. The box can be sealed by applying glue to the inside of the mating surfaces of the folded flaps prior to them being folded shut, or by applying tape to the outside of the flaps after they have been folded shut.
In many cases, the boxes are uniform in size, so providing apparatus that will fold the flaps and apply adhesive or tape thereto is not particularly difficult to do. The apparatus can be adjusted to suit the known width and the height of the boxes and there is usually no problem running the boxes through the case sealer once it has been adjusted properly.
However, sometimes the boxes are of different sizes coming down the same conveyor line. In these instances, a random case sealer is required, wherein the apparatus for folding the box flaps and applying adhesive or tape thereto adjusts automatically to suit the size of the box.
In prior art random case sealers, various sensors have been used to try to determine the exact size or position of the boxes entering the case sealer, and numerous actuators or other adjust mechanisms together with suitable control devices, have been used to adjust the position of the various folding and sealing components to suit the position and size of the box being sealed. A difficulty with this type of apparatus however, is that the boxes are often misshaped or underfilled or overfilled, so that they are not uniform in shape so the sensors often cannot determine the optimum position adjustments. The result is that the boxes get jammed in the apparatus shutting down the packaging line.
The jamming problem was largely overcome by the box sealer apparatus described in U.S. Pat. No. 5,685,814 issued to Tuan Vinh Le. In this patent, the folding and sealing components of the apparatus are gravitationally biased and positioned by contact with the actual box being sealed, so any variations in the shape of the box are automatically accommodated. Sometimes, however, the cardboard or box board used to make the cartons is not as thick or strong as it should be, or the boxes are underfilled, in which case the boxes can still be deformed during the sealing operation with undesirable results.